Skew rectification mechanism for fed paper

ABSTRACT

Skew rectification mechanism for fed paper. The skew rectification mechanism includes a first rotational shaft and a second rotational shaft arranged in parallel to a transverse reference axis of the paper. The rotational shafts are rotationally drivable by motors. A roller is coaxially fitted around each rotational shaft for guiding the paper to advance. In case of skew taking place in delivery of the paper, the first and second rotational shafts are rotated at different rotational speed to smoothly micro-rectify the skew of the paper.

BACKGROUND OF THE INVENTION

The present invention is related to a skew rectification mechanism for fed paper, and more particularly to a skew rectification mechanism in which the rotational shafts for feeding the paper can be rotated at different rotational speeds to micro-rectify the skew of the paper.

A conventional paper-feeding mechanism is applied to a printing machine or an office machine for faxing, printing or scanning papers. The conventional paper-feeding mechanism is generally equipped with rollers for picking, feeding and delivering the paper through the machine. In some cases, the paper is fed in a skewed state. In order to correct the skew of the paper, some measures have been developed. For example, U.S. Pat. No. 5,947,617 discloses a skew correction mechanism for a roll paper. The skew correction mechanism includes rotational shafts and rollers eccentrically mounted on the rotational shafts for pulling the paper back to its true position.

To speak in more detail, in the above patent, two rotational shafts are arranged in a paper-guiding section and interconnected by a coupling shaft. A first roller and a second roller are respectively eccentrically mounted on the rotational shafts. In the case that a skew sensor detects skew of a delivered paper, the control section actuates motors to drive gears, whereby one rotational shaft and the first roller is clockwise 180° rotated (defined as a correction period), while the other rotational shaft and the second roller are counterclockwise 180° rotated. Accordingly, the skewed paper is forcedly pulled back to its true position.

However, some problems exist in the above patent. For example, in the case that the sensor detects that the skew of the paper is over-corrected in the correction period, the control section will actuate the motors to make the first roller rotate in reverse direction, that is, counterclockwise rotate and make the second roller clockwise rotate in a next correction period. This can correct the overrun of the paper in the previous correction period. Alternatively, only one roller is rotated to correct the skew of the paper. In order to pull back the paper to its true position, two or even three correction periods are needed. This is because the rollers are eccentrically mounted on the rotational shafts. Each time the rollers rotate, the paper is driven and rectified by a relatively large angle. Therefore, such measure fails to achieve a micro-correction effect.

Furthermore, the eccentric roller has a form of a cam so that when the first and second rollers rotate to drive the paper, the paper will be waved. This makes it difficult to smoothly deliver the paper.

It is therefore tried by the applicant to provide an improved skew rectification mechanism for fed paper, which is able to micro-rectify the skew of the paper and deliver the paper more smoothly.

SUMMARY OF THE INVENTION

It is therefore a primary object of the present invention to provide an improved skew rectification mechanism for fed paper and a method for rectifying skew of fed paper. The skew rectification mechanism is able to micro-rectify skew of the paper in a more smooth state.

According to the above object, the skew rectification mechanism for fed paper of the present invention includes a first rotational shaft and a second rotational shaft positioned in parallel to a transverse reference axis of the paper. The first and second rotational shafts are rotationally drivable by motors. Two rollers are respectively coaxially mounted on the first and second rotational shafts. Each roller has a guiding surface for guiding and delivering the paper. In case of skew of the paper, the first and the second rotational shafts are rotated at different rotational speeds to rectify the skew and pull back the paper to its true position.

In the skew rectification mechanism for fed paper of the present invention, in case of skew of the paper, the first and the second rotational shafts are rotated in different rotational directions to rectify the skew and pull back the paper to its true position.

The method for rectifying skew of fed paper of the present invention includes steps of:

-   -   (a) arranging a detector in a position adjacent to a         paper-feeding path for detecting delivery condition of a paper         and transmitting detection signals to a control section; and     -   (b) using the control section to controllably actuate motors to         drive a first rotational shaft and a second rotational shaft to         rotate at different rotational speeds for rectifying skew of the         paper.

The present invention can be best understood through the following description and accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the skew rectification mechanism for fed paper of the present invention;

FIG. 2 is a top view of the skew rectification mechanism for fed paper of the present invention; and

FIG. 3 is a top view of the skew rectification mechanism for fed paper of the present invention according to FIG. 2, showing that the skewed paper is rectified and pulled back to its true position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 1 and 2. The skew rectification mechanism for fed paper of the present invention includes a paper receptacle 20 in which a roll of paper 21 is contained, a recording section 30 for recording data or information on the paper 21 fed from the paper receptacle 20, and at least one detector 40 arranged in a position adjacent to a paper-feeding path for detecting the delivery condition of the paper 21 and transmitting detection signals to a control section 50. The control section 50 serves to controllably actuate motors 61, 62 to drive gears 71, 72. A guide section 10 is arranged between the paper receptacle 20 and the recording section 30 for guiding and delivering the paper 21.

The guide section 10 includes a first rotational shaft 11 and a second rotational shaft 12 coaxially interconnected with each other by a coupling shaft 13. The first and second rotational shafts 11, 12 are parallel to a transverse reference axis χ of the paper 21. The first and second rotational shafts 11, 12 are respectively equipped with gears 14, 15 engaged with the gears 71, 72. Accordingly, the motors 61, 62 can controllably drive the first and second rotational shafts 11, 12 to rotate. Two rollers 16, 17 are respectively mounted on the first and second rotational shafts 11, 12. The rollers 16, 17 respectively have guiding surfaces 16′, 17′. In a preferred embodiment, the rollers 16, 17 are coaxially fitted around the first and second rotational shafts 11, 12. Accordingly, when the rollers 16, 17 are rotated along with the first and second rotational shafts 11, 12 to feed and rectify the paper 21, the waving condition of the paper 21 is minimized.

Referring to FIG. 3, when the detector 40 detects that the paper 21 is skewed rightward (as shown by solid lines of FIG. 3), the detector 40 will transmit a signal to the control section 50. In this case, the control section 50 will make the motor 62 and the gear 72 rotate at a rotational speed faster than that of the motor 61 and the gear 71. Under such circumstance, the rotational speed of the gear 15, the second rotational shaft 12 and the roller 17 is faster than the rotational speed of the gear 14, the first rotational shaft 11 and the roller 16. Accordingly, the paper 21 is rectified to move leftward back to its true position as shown by phantom lines of FIG. 3.

Alternatively, the control section 50 actuates the motor 62 to drive the second rotational shaft 12 and the second roller 17 to clockwise rotate, while actuating the motor 61 to drive the first rotational shaft 11 and the first roller 16 to counterclockwise rotate. Under such circumstance, the two rotational shafts 12, 11 are respectively forward and backward rotated to rectify the paper 21. Alternatively, only one of the rotational shafts 12, 11 is rotated, while the other of the rotational shafts 12, 11 is held still.

The present invention also provides a method for rectifying skew of fed paper. The method includes steps of:

-   -   (a) arranging a detector 40 in a position adjacent to a         paper-feeding path for detecting delivery condition of a paper         21 and transmitting detection signals to a control section 50;         and     -   (b) using the control section 50 to controllably actuate motors         61, 62 to drive a first rotational shaft 11 and a second         rotational shaft 12 to rotate at different rotational speeds for         rectifying skew of the paper 21.

According to a preferred embodiment, after step (b), the method further includes step (c) of making the first and second rotational shafts 11, 12 rotate at equal rotational speed to help in delivering the paper 21 to a recording section 30 after the skew of the paper 21 is rectified.

As mentioned above, the first and second rotational shafts 11, 12 can be rotated in reverse directions to rectify skew of the paper 21. It should be noted that after rectified, the control section 50 serves to controllably actuate the motors 61, 62 to drive the first and second rotational shafts 11, 12 to rotate in the same direction.

According to the above arrangement, the present invention has the following advantages over the conventional skew correction mechanism:

-   -   1. In contrast to the eccentrically arranged rollers of the         conventional skew correction mechanism, the rollers 16, 17 of         the present invention are coaxially mounted on the first and         second rotational shafts 11, 12. Therefore, when the rollers 16,         17 are rotated along with the first and second rotational shafts         11, 12 to feed and rectify the paper 21, the waving condition of         the paper 21 is minimized.     -   2. In contrast to the eccentrically arranged rollers of the         conventional skew correction mechanism for forcedly pulling back         the paper to its true position by a relatively large angle in         each correction period, the first rotational shaft 11 with the         first roller 16 and the second rotational shaft 12 with the         second roller 17 of the present invention are rotated at         different rotational speeds to micro-rectify the skew of the         paper.

The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from the spirit of the present invention. 

1. A skew rectification mechanism for fed paper, comprising at least one detector, a control section and a first and a second rotational shafts, the detector being arranged in a position adjacent to a paper-feeding path for detecting delivery condition of the paper and transmitting detection signals to the control section, the control section serving to controllably actuate motors to drive the first and second rotational shafts to rotate, the first and second rotational shafts being positioned in parallel to a transverse reference axis of the paper, two rollers being respectively coaxially mounted on the first and second rotational shafts.
 2. The skew rectification mechanism for fed paper as claimed in claim 1, wherein the first and second rotational shafts are rotatable in different rotational speeds.
 3. The skew rectification mechanism for fed paper as claimed in claim 1, wherein the first and second rotational shafts are rotatable in different directions.
 4. A method for rectifying skew of fed paper, comprising steps of: (a) arranging a detector in a position adjacent to a paper-feeding path for detecting delivery condition of a paper and transmitting detection signals to a control section; and (b) using the control section to controllably actuate motors to drive a first rotational shaft and a second rotational shaft to rotate at different rotational speeds for rectifying skew of the paper.
 5. The method for rectifying skew of fed paper as claimed in claim 4, wherein two rollers are respectively coaxially mounted on the first and second rotational shafts.
 6. The method for rectifying skew of fed paper as claimed in claim 4, wherein the first and second rotational shafts are rotatable in different directions.
 7. The method for rectifying skew of fed paper as claimed in claim 4, wherein in step (b), the first rotational shaft is not rotated, while the second rotational shaft is rotated.
 8. The method for rectifying skew of fed paper as claimed in claim 4, after step (b), further comprising a step (c) of making the first and second rotational shafts rotate at equal rotational speed.
 9. The method for rectifying skew of fed paper as claimed in claim 6, wherein after the first and second rotational shafts are rotated in different directions, further comprising a step (d) of making the first and second rotational shafts are rotated in the same direction. 